The present invention relates to a lift mechanism comprising a frame to which one end of a lift arm is pivoted on a horizontal shaft, and a platform pivoted at the other end of the lift arm on another horizontal shaft, the mechanism being controlled by an operating mechanism, which retains the platform substantially horizontal in irrespective to the position of the lift arm.
For maintaining horizontality of the platform, known lifts generally have a mechanically controlled mechanism e.g., a pantograph with steering links between the platform and the frame, or a hydraulic mechanism in which a double-acting cylinder between frame and lift arm is connected via two linkages to another double-acting cylinder between the lift arm and platform, or an electrically controlled mechanism in which a motor fixed to the lift arm may pivot the platform in relation to the lift arm controlled by a position-registering member associated with the platform.
An object of the invention is to provide a lift mechanism of the described type with a safety catch whereby the platform is retained in a substantially horizontal relation even if the control mechanism fails.
Such safety catch must be independent of hydraulic or electric systems.